Measurement of antibody to poly (adenosine diphosphate-ribose): its diagnostic value in systemic lupus erythematosus.

Poly (ADP-ribose) and dsDNA binding activity have been measured in sera from 61 patients with systemic lupus erythematosus (SLE) and 188 control sera from 20 normal individuals, 144 patients with clinically similar diseases and 24 patients with drug-induced anti-nuclear antibodies (ANA). Elevated poly (ADP-ribose) binding was not observed with normal sera. Five of 144 samples from diseases entering the differential diagnosis of SLE gave raised poly (ADP-ribose) binding compared with 12 in the 125I-dsDNA binding. Only two of these false positive samples gave elevated binding in the 14C-dsDNA assay. The apparent high specificity of the poly(ADP-ribose) assay was not observed with samples containing drug-induced ANA where 62% had elevated binding values. The frequency with which the poly(ADP-ribose) assay was positive with SLE sera (sensitivity) was lower than either of the dsDNA assays. This low sensitivity and the high rate of false positives in patients with drug-induced ANA limit the value of the poly(ADP-ribose) assay as a diagnostic test for SLE. However the restriction of poly(ADP-ribose) antibody to SLE and patients with drug-induced ANA together with the known role of poly(ADP-ribose) in DNA excision repair suggest that the antibody may be of fundamental significance.